1. Field of the Invention
This invention relates to an organo-polysiloxane composition which is useful as a surface treating agent for various cured rubber moldings for imparting non-tacky, water repellent, and lubricating properties to the rubber surface and forming an abrasion resistant coating. It also relates to a rubber article having such a coating.
2. Prior Art
Inert silicone oil and various curable organopolysiloxane compositions have been used for imparting non-tackiness and water repellency to rubber surfaces.
The inert silicone oil has high initial wear properties, but does not last long since it is readily shed from the substrate surface by physical action as weak as water washing.
The curable organopolysiloxane compositions used heretofore are typically those containing a both end hydroxyl-blocked diorganopolysiloxane, a Si--H group-containing organopolysiloxane and/or an organoalkoxysilane, and an organic tin compound. These compositions form on the substrate surface coatings which are acceptably tack-free and water repellent, but poor in lubricity and wear resistance. It is possible to improve adhesiveness with a substrate and lubricity, which lead to wear resistance, by adding a mixture or reaction product of an organopolysiloxane having an epoxy group such as glycidoxy group and epoxycyclohexyl group and alkoxysilane or siloxane having an amino group (Japan Kokoku Nos. 54-43023, 56-19813 and 56-47864), but the improvement is not yet fully attained. It is also possible to improve lubricity and wear resistance by adding inert silicone oil to such organopolysiloxane compositions containing a both end hydroxyl-blocked diorganopolysiloxane, a Si--H group-containing organopolysiloxane and/or an organoalkoxysilane, and an organic tin compound (Japan Kokoku No. 4-80072), but the coatings are not satisfactorily durably wear resistant where frictional forces are repeatedly applied. There is a strong desire for improving coatings to be durably wear resistant.